Synatic foam design modifications

ABSTRACT

A drilling riser buoyancy module comprises two opposite complementary halves each having complementary co-axially extending central opening for a flow line and at least five complementary axially extending secondary openings for receiving auxiliary lines. Each complementary half comprising foam bounded by an interior surface and an exterior surface. A portion of the interior surfaces of complementary halves contact each another. Each exterior surface of the two halves comprises (i) a first flat exterior surface segment radially opposite an associated first flat exterior surface segment of the other half, (ii) a second flat exterior surface segment radially opposite an associated second flat exterior surface segment of the other half, where the second flat exterior surface segment is circumferentially adjacent to the first flat exterior surface segment and (iii) a plurality of partially-cylindrical exterior surface segments whose aggregate circumferential length is greater than aggregate length of the first and second flat exterior surface segments of the two opposite detachable complementary halves.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application Ser. No. 62/113,056, filed Feb. 6, 2015, the contents of which are incorporated herein by reference.

FIELD

The invention relates to the field of buoyancy modules, and in particular to driller riser buoyancy modules.

BACKGROUND

Driller riser buoyancy modules are used for providing a conduit for various lines of a drill string between the oil rig and ocean floor.

Driller riser buoyancy modules for subsea riser pipes are often made of syntactic foam solid cores covered with a tough exterior shell. A conventional driller riser buoyancy module includes two detachable complementary halves each having a complementary co-axially extending primary central opening for a main flow line and a plurality of complementary axially extending secondary openings for receiving auxiliary lines. Each opposite detachable complementary half comprises foam (e.g., syntactic) bounded by an interior surface and a rugged exterior shell. For example, a conventional drilling riser buoyancy module is disclosed U.S. Pat. No. 7,628,665. Each driller riser buoyancy half disclosed in this prior art patent includes a semi-cylindrical cross-sectional exterior surface, so when the halves are combined the cross-sectional exterior of the buoyancy module is cylindrical. An example of a buoyancy module 10 having a cylindrical cross-sectional exterior is illustrated in FIG. 1.

FIG. 2 is a cross-sectional illustration of a second known driller riser buoyancy module 12. Notably, the exterior of each detachable complementary half 14, 16 includes a flat segment 18, 20, respectively, and partially-cylindrical exterior surface segments 22-25. The flat segments 18, 20 provide surfaces that the buoyancy module rests onto when stacked (e.g., on a ship). This configuration is often referred to as a 60-degree flat, and is conventional for a riser system with five auxiliary lines.

A problem with the driller riser buoyancy module 12 illustrated in FIG. 2 is that when a relatively large number of riser joints are stacked (e.g., 9 or more riser joints laid atop one another substantially horizontally), risers on the bottom of the stack are stressed in compression and the compressive forces may cause damage to the riser (e.g., cracking of the foam).

There is a need for an improved driller riser buoyancy module.

BRIEF SUMMARY

A drilling riser buoyancy module comprises two opposite detachable complementary halves each having a complementary co-axially extending primary central opening for a main flow line and first and second complementary axially extending secondary openings radially adjacent and on opposite sides of the primary central opening for receiving and holding first and second auxiliary lines, respectively. Each opposite detachable complementary half comprising syntactic foam bounded by an interior surface and an exterior surface. A first of the opposite detachable complementary halves includes a third co-axial auxiliary line opening and a second of the opposite detachable complementary halves includes a fourth co-axial auxiliary line opening and a fifth co-axial auxiliary line opening. A portion of the interior surfaces of complementary halves are configured and arranged to contact each another. Each exterior surface of the two halves comprises (i) a first flat exterior surface segment radially opposite an associated first flat exterior surface segment of the other half, (ii) a second flat exterior surface segment radially opposite an associated second flat exterior surface segment of the other half, where the second flat exterior surface segment is circumferentially adjacent to the first flat exterior surface segment and (iii) a plurality of partially-cylindrical exterior surface segments whose aggregate circumferential length is greater than aggregate length of the first and second flat exterior surface segments of the two opposite detachable complementary halves.

The first and second of complementary axially extending secondary openings may be substantially semi-cylindrical.

A first of the two opposite detachable complementary halves includes a first axial opening formed in the interior surface of the first of the two opposite detachable complementary halves.

A second of the two opposite detachable complementary halves includes a second axial opening formed in the interior surface of the second of the two opposite detachable complementary halves and a third axial opening formed in the interior surface of the second of the two opposite detachable complementary halves.

A drilling riser buoyancy module comprises two opposite detachable complementary halves each having complementary co-axially extending primary central opening for a main flow line and at least five complementary axially extending secondary openings for receiving and holding auxiliary lines. Each opposite detachable complementary half comprising foam bounded by an interior surface and an exterior surface. A portion of the interior surfaces of complementary halves are configured and arranged to contact each another. Each exterior surface of the two halves comprises (i) a first flat exterior surface segment radially opposite an associated first flat exterior surface segment of the other half, (ii) a second flat exterior surface segment radially opposite an associated second flat exterior surface segment of the other half, where the second flat exterior surface segment is circumferentially adjacent to the first flat exterior surface segment and (iii) a plurality of partially-cylindrical exterior surface segments whose aggregate circumferential length is greater than aggregate length of the first and second flat exterior surface segments of the two opposite detachable complementary halves.

These and other objects, features and advantages of the present invention will become apparent in light of the following detailed description of preferred embodiments thereof, as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional illustration of a first prior art buoyancy module;

FIG. 2 is a cross sectional illustration of a second prior art buoyancy module; and

FIG. 3 is a cross sectional illustration of an improved buoyancy module;

DETAILED DESCRIPTION

FIG. 3 is a cross sectional illustration of a drilling riser buoyancy module 30. The module 30 includes two opposite detachable complementary halves 32, 34. The first detachable complementary half 32 includes a first primary semi-cylindrical opening 36 formed by a plurality of curved sidewalls segments 37 a, 37 b each having a radius R. The second detachable complementary half 34 includes a second primary semi-cylindrical opening 38 formed by a plurality of curved sidewalls segments 39 a, 39 b and 39 c each having a radius R. The first and second primary semi-cylindrical openings 36, 38 formed by the sidewall segments 37 a, 37 b, 39 a, 39 b and 39 c form a primary central opening 40 sized to surround a riser pipe 41.

The first detachable complementary half 32 includes a first axially extending semi-cylindrical secondary opening 42 radially adjacent the primary central opening 40. The first detachable complementary halve 32 also includes a second axially extending semi-cylindrical secondary opening 44 radially adjacent and on opposite sides of the primary central opening 40. The secondary openings 42, 44 are radially separated by the central opening 40. The second detachable complementary half 34 includes a third axially extending semi-cylindrical secondary opening 46 radially adjacent to the primary central opening 40. The second detachable complementary half 32 also includes a fourth axially extending semi-cylindrical secondary opening 48 radially adjacent to the primary central opening 40. The first and third semi-cylindrical secondary openings 42, 46 cooperate to form a first accessory opening 50, and the second and fourth semi-cylindrical openings 44, 48 cooperate to form a second accessory opening 52. The first and second accessary openings 50, 52 are radially separated by the central opening 40.

The first detachable complementary half 32 also includes an axially extending third accessary opening 54. The second detachable complementary half 34 includes axially extending fourth and fifth accessary openings 56, 58.

The first detachable complementary half 32 comprises syntactic foam bounded by the sidewall segments 37 a, 37 b and a protective exterior surface 60. Interior surface of the first detachable complementary halve 32 forms the third accessory opening 54. The second detachable complementary halve 34 comprises syntactic foam bounded by sidewall segments 39 a, 39 b and 39 c and a protective exterior surface 62. The interior surface of complementary halve 34 partially forms the fourth and fifth accessary openings 56, 58.

As shown in FIG. 3, a portion of the interior surfaces of the complementary halves 32, 34 are configured and arranged to contact each another, for example at 64, and the complementary halves 32, 34 may be held in contact with fasteners (e.g., bolts) and straps (not shown).

The exterior surfaces 60, 62 of the detachable complementary halves 32, 34, respectively, may comprise a plurality of curved and straight segments. For example, referring to FIG. 3, the first exterior surface 60 may include a first flat exterior surface segment 66 radially opposite an associated first flat exterior surface segment 68 of the second exterior surface 62. The first exterior surface 60 may also include a second flat exterior surface segment 70 radially opposite an associated second flat exterior surface segment 72 of the other half, where the second flat exterior surface segments 70, 72 are circumferentially adjacent to the first flat exterior surface segments 66, 68 respectively.

In addition, the first exterior surface 60 also includes a plurality of curved segments 74, 76. The segments may have a radius R from the longitudinal center line of the drilling riser buoyancy module 30. The second exterior surface 60 also includes a plurality of curved segments 78, 80. These curved segments may also be characterized as having a radius R from the longitudinal center line of the drilling riser buoyancy module 30. The aggregate circumferential length of the plurality of partially-cylindrical exterior surface segments 74, 76, 78 and 80 may be greater than aggregate length of the flat exterior surface segments 66, 68, 70 and 72.

Although the present invention has been shown and described with respect to several preferred embodiments thereof, various changes, omissions and additions to the faun and detail thereof, may be made therein, without departing from the spirit and scope of the invention. 

What is claimed is:
 1. A drilling riser buoyancy module comprising: two opposite detachable complementary halves each having a complementary co-axially extending primary central opening for a main flow line and first and second complementary axially extending secondary openings radially adjacent and on opposite sides of the primary central opening for receiving and holding first and second auxiliary lines respectively, each opposite detachable complementary half comprising syntactic foam bounded by an interior surface and an exterior surface, where a first of the opposite detachable complementary halves includes a third co-axial auxiliary line opening and a second of the opposite detachable complementary halves includes a fourth co-axial auxiliary line opening and a fifth co-axial auxiliary line opening; where a portion of the interior surfaces of complementary halves are configured and arranged to contact each another, and where each exterior surface of the two opposite detachable complementary halves comprises (i) a first flat exterior surface segment radially opposite an associated first flat exterior surface segment of the other half, (ii) a second flat exterior surface segment radially opposite an associated second flat exterior surface segment of the other half, where the second flat exterior surface segment is peripherally adjacent to the first flat exterior surface segment and (iii) a plurality of partially-cylindrical exterior surface segments whose aggregate circumferential length is greater than aggregate length of the first and second flat exterior surface segments of the two opposite detachable complementary halves.
 2. The drilling riser buoyancy module of claim 1, where the plurality of complementary axially extending secondary openings are substantially semi-cylindrical.
 3. The drilling riser buoyancy module of claim 1, where a first of the two opposite detachable complementary halves includes a first axial opening formed in the interior surface of the first of the two opposite detachable complementary halves.
 4. The drilling riser buoyancy module of claim 2, where a second of the two opposite detachable complementary halves includes a second axial opening formed in the interior surface of the second of the two opposite detachable complementary halves and a third axial opening formed in the interior surface of the second of the two opposite detachable complementary halves.
 5. A drilling riser buoyancy module comprising: two opposite detachable complementary halves each having complementary co-axially extending primary central opening for a main flow line and at least five complementary axially extending secondary openings for receiving and holding auxiliary lines, each opposite detachable complementary half comprising foam bounded by an interior surface and an exterior surface, where a portion of the interior surfaces of complementary halves are configured and arranged to contact each another, and where each exterior surface of the two halves comprises (i) a first flat exterior surface segment radially opposite an associated first flat exterior surface segment of the other half, (ii) a second flat exterior surface segment radially opposite an associated second flat exterior surface segment of the other half, where the second flat exterior surface segment is circumferentially adjacent to the first flat exterior surface segment and (iii) a plurality of partially-cylindrical exterior surface segments whose aggregate circumferential length is greater than aggregate length of the first and second flat exterior surface segments of the two opposite detachable complementary halves. 